NATURE 
[May 16, rome 
worn forms, which must have travelled from higher 
levels. 
Sir Ray Lankester, K.C.B.: Flint implements 
from beneath the Red Crag of Suffolk. Many 
worked flints of a previously unknown shape, viz. 
that of an eagle’s beak (rostro-carinate) and of other 
forms, have been discovered by Mr. Moir, of Ipswich, 
in the bone-bed of the Suffolk Crag. Several of 
these were exhibited, and also three rostro-carinate 
flint implements from the mid-glacial sands of 
Suffolk. Both the Red Crag sea and that of the 
mid-Glacial period swept these implements from an 
old Suffolls land surface. Those from below the Red 
Crag are of Pliocene, and possibly of Miocene, age. 
NaruraL History.—Dr. H. B. Fantham and Dr. 
Annie Porter: Nosema apis, the parasite of Isle of 
Wight disease in bees. This pathogenic protozoon 
was discovered in 1g06 by the exhibitors, and shown 
experimentally by them to be pathogenic, not only to 
hive bees, but also to wasps and mason bees. The 
parasite, which belongs to the Microsporidia, is allied 
to the organism causing pébrine in silkworms. 
Mr. H. R. A. Mallock, F.R.S.: Apparatus for 
showing the disappearance of iridescent colouring 
under mechanical pressure. The coloured scales are 
placed between a flat plate and lens of quartz on the 
stage of a microscope and viewed during the process 
of compression with a low-power objective. The 
seales in the compressor were from Ornithoptera 
Poseidon. These are bright green by reflected light, 
but appear red when the light is transmitted. On 
applying pressure to a scale the colour first changes 
and then disappears, thus showing that its origin is 
due to the structure of the scale and not to colouring 
matter. 
Dr. C. J. Patten: A selection of specimens and 
photographs illustrating some features in bird migra- 
tion as observed during eight weeks’ residence at the 
Tuskar Rock Lighthouse, Co. Wexford. The follow- 
ing points are noteworthy :—first, that in a com- 
paratively short period, several rare birds—some new 
to Ireland—have been secured, which, had _ they 
reached the mainland, might never have been re- 
corded; secondly, that birds supposed by some 
observers not to migrate, or at most to do so ina 
very desultory manner, have been found migrating in 
considerable numbers together; and thirdly, that re- 
markable variations in size and plumage may be seen 
in some species. 
Prof. E. B. Poulton, F.R.S.: Butterfly mimicry 
and mutation. It has been argued, especially by 
Prof. Punnett, that the mimetic patterns of butterflies 
arose, ready-made and complete, by a sudden ‘‘ muta- 
tion.” The examples which he has specially men- 
tioned are the mimetic females of the African Papilio 
dardanus and the two mimetic forms of Euralia 
wahlbergi. The exhibited series shows (1) the 
gradual origin of mimicry in the former, through the 
transitional form trimeni leading from the pattern of 
the non-mimetic females in Madagascar and Abyssinia 
to the mimetic hippocoon female; (2) the existence 
of a roughly mimetic representative of the two 
mimetic forms of the Euralia, in an allied species, 
FE. dinarcha, and of intermediates which breed true, 
and are therefore not hybrids (heterozygotes), in a 
still more closely allied Euralia: all these bred by Mr. 
W. A. Lamborn in the Lagos district; (3) the four 
sharply separated mimetic patterns of a Pseudacrzea, 
collected by Mr. C. A. Wiggins at Entebbe, connected 
by intermediates and running into one another on the 
islands in the Victoria Nyanza, where the Acraine 
models are relatively scarce. The latter collected by 
Mr..G. D. H. Carpenter. 
Astronomy.—Dr. Percival Lowell (Lowell Observa- 
NO, 2220, VOL: 60]] 
tory, U.S.A.): (1) Spectroscopic discovery of the. rota- 
tion period of Uranus. Two enlarged copies of two 
(out of seven measured) of the original spectrograms 
taken in September, 1911, by Dr. V. M. Slipher, one 
with the camera to the west, one with it to the east, of 
the telescope, thus reversing the direction of the tilt. 
The spectrum of Uranus appears in the middle flanked 
by the two comparison spectra. ‘The slit was parallel 
to the sateJlite’s orbital planes. Measurement of the 
original negatives gives a rotation spin of toh. 45m. 
retrograde. (2) Autumnal morning hoar-frost on 
Mars. Enlarged positives from the original negatives 
of Mars, taken November 14, 1912, 39° of longitude 
apart, showing hoar-frost on sunrise edge of the disc 
30° to right of topmost point. The hoar-frost was 
studied for two months, and a memoir is in course of 
publication. Theory shows that 60° latitude is 
exactly where it should first have appeared. | 
(3) Halley’s comet: last appearance. Photographs 
with the 4o-in. Lowell reflector by Mr. C. O. Lamp- 
land, on May 23, 27, and 30, 1911; also positive 
showing the positions in which the comet was photo- 
graphed by him up to June 1 inclusive. These are 
the last views got of the comet as it left. (4) Comet 
Brooks, 1911. Objective-prism spectrogram taken on 
October 28, 1911, and November 2, 1911, show mono- 
chromatic images of the comet, and register the fact 
that the tail was composed almost entirely of carbon 
monoxide, while the hydrocarbons and cyanogen were 
conspicuous in the head. 
Prof. H. F. Newall, F.R.S.: Photographs of the 
spectrum of Nova Geminorum, taken at Cambridge 
Observatory. _ Nova Geminorum was discovered by 
Enebo on March 12, 1912. It was not recorded at 
Harvard College Observatory on plates taken on 
March 10, but appeared as a star of fifth magnitude 
on a plate taken on March 11. Since its first maxi- 
mum brightness (magnitude about 3:0) the star has 
faded, with fluctuations, to magnitude 5.0 on 
March 18, 1nagnitude 6-0 on April 1, 7-0 on April 15. 
The photographs of spectra exhibited have been pre- 
pared from negatives picked out of a series of forty 
plates secured by Mr. Stratton on thirty-six nights, 
between March 15 and April 29, with the two-prism 
spectrograph attached to the 25-in. equatorial, with 
exposures varying from twenty-five minutes to five 
hours. They illustrate the rapid changes in the 
nature of the light emitted, especially in the first ten 
days after the outburst of the star on March 11. 
Puysics.—The National Physical Laboratory: 
Apparatus for measuring the visibility of point sources 
of light. (Exhibited by Mr. C. C. Paterson and Mr. 
B. P. Dudding.) The apparatus contains a pin-hole 
of known area with a flame of known intrinsic bright- 
ness behind it. The intensity of the transmitted light 
can be varied at will by calibrated absorption wedges 
placed in the beam to the observer’s eye, the com- 
bination forming a variable standard point of light 
of known candle-power. The distant source of light 
is seen in the same field of view as the standard 
point source, and the latter is adjusted to be equal 
to it in brightness. There are arrangements for 
illuminating the background of the standard pin- 
hole when observations are being made on nights 
which are not quite dark. The lower limit of visi- 
bility is that of a point source of about one ten- 
millionth of a candle one metre from the eye of an 
observer. 
Mr. C. T. R. Wilson: (1) Apparatus for making 
visible the tracks of ionising particles by vapour con- 
densed upon the ions set free along the paths. 
(2) Cloud photographs showing the nature of the 
ionisation. produced by different kinds of rays. By 
the sudden dropping of the floor of a cloud chamber, 
